1. Field of the Invention
The present invention relates to a robot hand and a robot hand finger and, more particularly, to a robot hand finger that is capable of hooking and a hand that is capable of grasping a stuff stably by having the hooking-available robot hand finger.
2. Description of the Background Art
FIG. 1 is a plan view of a a multi-articular robot hand in accordance with a conventional art, and FIG. 2 is a side view showing an operation state of the robot hand of FIG. 1.
The conventional robot hand includes a thumb 20A, a forefinger 20B, middle finger 20C, third finger 20D and a little finger 20E in combination with a bracket 42 attached at front portion of an arm 41 of an industrial robot.
The thumb 20A is formed by connecting three phalanxes 25-27 to two axes 34-35.
The forefinger 20B, the middle finger 20C, the third finger 20D and the little finger 20E are formed by connecting four phalanxes 21-24 to three axes 31-33.
A pneumatic cylinder 43 is installed inside each of the phalanxes 21-24 and 26 of fingers 20A-20E, and a vertical guide hole 45 is formed at a front end of a piston rod 44.
A pair of protrusions 46 are formed facing each other at a distal end of phalanxes 22-24, 26-27 except the distal phalanx 21 and 25 of the fingers 20A-20E, and a diagonal cam hole 47 and an axial hole 51 are formed at the protrusion 46.
A pair of support protrusions 48 are formed facing each other at a proximal end of the phalanxes 21-23 and 25-26 except the proximal phalanxes 24 and 27 of the fingers 20A-20E, and an axial hole 49 a long hole 50 are formed at the support protrusion 48.
The protrusion 46 is inserted between the support protrusions 48, and a central piece 52 is inserted penetrating the axial holes 49 and 51 so that the phalanx can be rotated.
A support pin 53 is installed penetrating the long hole 50, the vertical guide hole 45 of the piston rod 44 and the cam hole 47, so as to make a hooking movement. Air injection ports 54 and 55 are formed at the pneumatic cylinder 43.
As shown in FIGS. 1 and 2, the robot hand can make a hooking movement with the axis portions 31-35 by the pneumatic pressure supplied to each pneumatic cylinder 43 under the control of a separately installed controller (not shown).
The operation of the conventional multi-articular robot hand constructed as described above will now be described.
When air is supplied to the air injection port 54 of the pneumatic cylinder 43 by the controller (not shown), the piston rod 44 is moved forwardly, the support pin 53 is guided to be downwardly moved by the cam hole 47, and the phalanx 22 makes an upward hooking movement centering around the central pin 52.
When air is supplied to the other air injection port 55 of the pneumatic cylinder 43, the phalanx is unfolded as the above process is reversely performed.
In order to make the fingers 20A-20E to move, the conventional multi-articular robot hand needs the pneumatic cylinder 43 as many as the axes 31-35, resulting in that the construction elements of the robot hand is increased in number and its volume is enlarged.
In addition, the fingers 20A-20E are disposed in a straight line and can not make a horizontal movement. Thus, if a working stuff has a circular form, the fingers can hardly grasp it.
Moreover, a grasping force of the hand is to be changed suitably and actively depending on the working stuff to be grasped so as to stably grasp the working stuff and prevent a damage. But the conventional robot hand fails to suitably and actively change the grasping force of the hand according to the working stuff.